The present invention pertains to a motor vehicle hydraulic brake master cylinder with a pressure transducer integrated with the master cylinder primary actuator piston.
Motor vehicle hydraulic brake systems include a so-called master cylinder or actuator which converts mechanical actuation of the brake pedal to hydraulic pressure for the brake hydraulic circuits. In the development of hydraulic brake systems, it is desirable to minimize the number of hydraulic fluid ports and connections between any part of the hydraulic system, including the master cylinder, to minimize problems associated with production and assembly of these parts and potential leakage paths for hydraulic fluid from the system. Moreover, due to space limitations in many motor vehicle engine compartments, it is also desirable to eliminate space required for hydraulic conduits or devices mounted on the exterior of a brake master cylinder housing, such as pressure transducers or other signal generating devices.
However, motor vehicle hydraulic brake systems typically also require a signal generating device or sensor which is operable to transfer a signal related to hydraulic brake pressure for various purposes, including actuation of brake lights, or as a signal input to a braking system controller, as well as possibly other uses of a brake pressure signal in modern automotive vehicle control systems. Accordingly, there has been a strongly felt need to provide for a signal generating or transducer device which may be integrated into the hydraulic brake master cylinder assembly without adding structure external to the master cylinder housing and without providing a point of connection to the cylinder housing which could be a potential leakage path for hydraulic fluid. It is to these ends that the present invention has been developed.
The present invention provides an improved arrangement of a hydraulic brake master cylinder for a motor vehicle which includes a signal generating pressure transducer which is integrated into the master cylinder housing. In particular, the present invention provides a hydraulic brake master cylinder with a pressure transducer mounted in one of the master cylinder pistons, preferably the primary master cylinder brake actuating piston.
In accordance with another aspect of the present invention, an automotive vehicle hydraulic brake system includes a master cylinder with a pressure transducer mounted in the so-called primary master cylinder piston and which includes a signal conductor path formed by a connector between the transducer and the brake actuator link or rod which may, for example, be the so-called booster output rod from the brake system vacuum force amplifier or booster, or the like.
The invention provides for integration of a pressure transducer operable to sense hydraulic pressure within the master cylinder as applied by the primary master cylinder piston and wherein the pressure signal may be transmitted out of the master cylinder electrically and through the piston actuator or so-called booster actuator output rod. Accordingly, a brake pressure signal may be taken from the master cylinder without adding an external point of connection with the master cylinder fluid chambers or adding a device connected to the exterior of the master cylinder housing.
Those skilled in the art will further appreciate the advantages and superior features of the invention upon reading the detailed description which follows in conjunction with the drawing.